Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 16 of 16 for “"charge transfer states"”.
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Charge transfer states in alkali metals
… revealed by both types of measurement is charge transfer from the alkali conduction band to localized orbitals bound on the impurities. The excitation spectra of halogen impurities in alkali metals have been investigated throughout the photon energy range from 5 eV to 12 eV. Threshold …
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DNA Directed Organic Semiconductor Interactions Controlling Excitons, Charge Transfer States, and Singlet Fission
Excited states in organic semiconductors are generated, transported, and converted through π-orbital interactions between multiple molecules. Hence, efficiency depends on the relative geometries between molecules. Yet, control over spatial assembly of organic semiconductors is challenging. Large …
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Enhancing the efficiency of organic LEDs through spin-orbit coupling of charge-transfer states
… effects is examined. Because only singlet spin states, statistically one quarter of the total possible states, emit fluorescent light, it has generally been thought that a maximum of 25% efficiency could be attained without the addition of an emissive phosphor. Here, we present evidence that …
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Singlet Exciton Fission in Acene Dimer and Diradicaloid Molecules
… governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. The process exhibits a sensitivity to solvent polarity and competes with geometric relaxation in the singlet state, while subsequent …
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Fluctuations and exciton dynamics in molecular semiconductors
… this consistent description of the electronic states, it is discussed how fluctuations act on different materials and how they impact charge transport properties. These deliberations lead to non-trivial design rules for future materials with high charge mobilities that have been independently …
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Quantum chemical investigation of electron delocalization patterns during photoexcitation in Fischer carbene complexes: a theoretical study
… materials. Specifically, the ground and excited states of various organometallic photosensitizers are investigated using FALDI in order to probe the degree of electron delocalization present in metal-to-ligand charge transfer states.
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Characterization of Local field effect in organic film using pressure technique
… measurements of pressure effects on exciplex charge-transfer states in bulk heterojunction films are performed to show change in emission lifetimes. This work could provide a better understanding of the singlet-triplet exciton coupling rates and have a significant impact on device optimization …
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The Role of Disorder in the Charge Dissociation and Recombination Processes of Organic Photovoltaic Materials
… fully quantum mechanical model of the electronic states of a bulk-heterojunction interface to investigate how presence of disorder in OPVs affects the recombination of triplet charge-transfer states and influences the free energy of an electron as it separates away from the interface into the free …
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Synthesis and Characterisation of Singlet Fission and Open-Shell Materials for Optoelectronic Application
… dependent on the extent of electronic coupling. Charge-transfer states were also found to mediate singlet fission. We revealed the traditional design principles for singlet fission dimers cannot be applied to modern polarisable systems. The relationship between molecular symmetry and …
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Femtosecond Time-Resolved Laser Spectroscopic Studies on the Electron Dynamics in Heterostructured Nanomaterials
… has been focused on the photoinduced charge carrier dynamics in heterostructured nanomaterials. Of particular interest are type-II heterostructures, where the relative band alignment of their constituent semiconductor materials promotes a spatial separation of the electron and hole …
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Exciton Dynamics in DNA-Chromophore Assemblies
… over the spatiotemporal evolution of excited states. Natural light harvesting systems achieve the required control through precise molecular placement; however, it has been challenging to emulate multi-chromophore organization in synthetic systems. Towards mimicking these nat- ural …
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Electronic processes in organic optoelectronics : insights gained through modeling and magnetic field effects
… Certain organics are capable of dividing excited states in a process termed singlet fission, which can increase the maximum theoretical efficiency of an OPV by a factor of nearly 1/3. The MFEs on photocurrent measurements from our collaborators are combined with theoretical models to determine …
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Theoretical investigations of the electronic processes in organic photovoltaics
… related to organic photovoltaics, such as the charge separation processes at the organic/organic interface, which can only be remedied by a combined theoretical and experimental effort. In this thesis we use a variety of computational techniques to address current questions in the field or …
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Photophysics of Hybrid Perovskites with Electroactive Molecules
… strength of this hybrid coupling. Photoinduced charge transfer and a sub-gap charge transfer state are demonstrated in the 2D perovskite (Cz-Ci)2PbI4, and these properties are shown to be tunable through the chain length of the alkylammonium spacer, Ci. In (Pyr-Ci)2PbI4, the linker length …
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Coupled-Cluster Methods for Large Molecular Systems Through Massive Parallelism and Reduced-Scaling Approaches
… pair natural orbital (PNO) approach to excited states through the equation-of-motion coupled cluster singles and doubles (EOM-CCSD) method. (C. Peng, M. C. Clement, and E. F. Valeev, textit{submitted}) We simulate the PNO-EOM-CCSD method using an existing massively parallel canonical EOM-CCSD …
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Generation, recombination and extraction of charges in polymer
… organic materials systems, the yield of charge generation can be very efficient. However, a detailed understanding of the free charge carrier generation mechanisms at the donor acceptor interface and the energy loss associated with it needs to be established. Moreover, organic solar cells …